110 JOURNAL OF THE [October, 



date of writing these notes, I am more familiar with two marine 

 fossil deposits, discovered by myself, than any one else who has 

 made the study of the diatoms a specialty. In one of these the 

 Polycystinae predominate above the Diatomaceae, sponge spicules, 

 and Foraminifera. This is the St. Stephens, Ala., eocene de- 

 posit, of which this Society possesses selected slides. Yet the 

 diatoms are very abundant therein, and of many species. The 

 other is the marine fossil deposit existing in the Florida phosphate 

 rock area around Tampa, Fla., wherein the Diatomaceae pre- 

 dominate above the Polycystinae and silicious sponge spicules, 

 and where calcareous Foraminifera seem to be entirely absent. 

 The egg-shaped or ovoid silicious gemmules of sponges (?) are also 

 very abundant therein. Taking an example right at hand, the 

 world has been supplied with cleaned diatoms from the harbor 

 clays and muds of Mobile Bay, in which are always associated 

 diatoms, a few species of Polycystinge, silicious sponge spicules, 

 and rhizopods of several species, and more particularly the sili- 

 cious shell-building ones known as Difflugia pyrifor7nis^ Arcella, 

 and others. The silicious bodies called Dictyocha also abound, 

 and the marine Foraminifera which secrete calcareous or chitin- 

 ous shells. The mineralized calcareous cementstein of Sendai, 

 Japan, and of the islands of Mor and Fur, situated off the northern 

 coast line of Europe, when dissolved in acid, yield masses of Dia- 

 tomaceae, sponge spicules, and Polycystinse, the diatom in the 

 several cases predominating. The fossil diatomaceous clays of 

 the Atlantic seaboard, from Southern New Jersey to Charleston, 

 S. C, at Richmond and other points, always yield a small pro- 

 portion of Polycystinae in combination with a tenfold percentage 

 of the Diatomaceae. The fossil deposits of the Californian coast 

 line yield diatoms in combination with Polycystinae and sponge 

 spicules, and so on ad infinitum. 



Passing from the fossil marine deposits which I have put upon 

 record, I will mention two extensive and rich deposits of fresh- 

 water origin. First, the lacustrine fossil deposit at Montgom- 

 ery, Ala., where billions of sponge spicules are associated with a 

 stratum of diatom frustules over twenty feet in thickness and of 

 extraordinary extension. Second, the marine marsh fluviatile 

 deposit found by myself a year or so ago about a mile north of 

 Mobile, on the western bank of Mobile River, which deposit is 



